High resolution complementary metal-oxide-semiconductor (CMOS) and charge-coupled device (CCD) image sensors are highly demanded in today's market for their use in acquiring high quality images. For example, such image sensors may be used in digital cameras, smart phone cameras, and other digital devices including camera functionality. However, in order to keep die sizes small, pixel sizes used in these image sensors may be reduced. The smaller pixel size lowers the image sensor's ability to detect a number of impinging photons, thus causing images acquired by the image sensor to have a lower signal-to-noise ratio (SNR). The SNR decreases further when the image sensor is being used in a low light condition.